Organic treatments for control of pepper weevil (Coleoptera: Curculionidae)

Abstract

The pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) is a major pest of pepper (Capsicum spp.; Solanales: Solanaceae) in the southern United States, Mexico, Central America and the Caribbean. Feeding and oviposition cause flower and fruit abscission and internal fruit damage resulting in serious yield losses. Females lay eggs in flower buds and small fruits, shielding larvae from contact pesticides, leaving only the adult stage vulnerable. The purpose of this study was to investigate low-risk and organic products for use against the pepper weevil to provide both organic and conventional growers with more control options. A neem product (Ecozin® 1.2% ME), kaolin clay (Surround® WP), diatomaceous earth (Red Lake Earth®) and a product based on plant terpenes (Requiem®), were tested in lab and field trials for efficacy against pepper weevil. The neem product did not reduce feeding or oviposition in lab choice and no choice tests, so it was not tested in the field. Kaolin clay, diatomaceous earth and Requiem reduced feeding and oviposition in lab trials. Spring and fall field tests of these products were conducted in small plots along with a standard pesticide rotation of Actara and Vydate and an untreated control. The only treatment to increase marketable yield was the standard pesticide rotation. In the spring field trial, the standard treatment doubled yield per plant compared to the untreated controls but the yield was not different from those in the kaolin clay and surround plots. While the organic products did not increase marketable yield significantly, they did decrease overall damage, indicating possible usefulness in combination with conventional insecticides or in low population pressure by spraying early and following appropriate cultural practices such as adequate fallow periods and crop destruction. We recommend further testing of diatomaceous earth in particular in combination with conventional and organic insecticides as part of future IPM program research.